Polypeptide

How does a polypeptide differ from a peptide?

"Polypeptide" is the general chemistry term for any chain of amino acids linked by peptide bonds, without a fixed length limit. Peptide is FDA's narrower regulatory category inside that range: a chain of 40 amino acids or fewer, regulated as a drug rather than a biological product, while a chain longer than 40 amino acids is a protein [4]. So a short polypeptide and an FDA peptide can be the same molecule described two ways, one by chemistry, one by regulation.

Which approved drugs are described as polypeptides?

Pregnyl, a chorionic gonadotropin product, is labeled "a polypeptide hormone produced by the human placenta" [1]. Two other familiar drugs are amino-acid chains their labels describe by formula or sequence rather than by the word. Humulin R (insulin human) is made by recombinant DNA technology, has a molecular weight of 5.808 kDa, and is indicated to improve glycemic control in adult and pediatric patients with diabetes [2]. Forteo (teriparatide) is "a recombinant human parathyroid hormone analog (PTH 1-34)" with a sequence identical to the 34 N-terminal amino acids of human PTH, dosed at 20 mcg subcutaneously once a day [3].